This invention relates generally to the field of catalysis, and more particularly relates to multinuclear complexes of transition metals and unsaturated nitrogenous ligands that are useful, inter alia, as polymerization catalysts. The invention additionally relates to methods for using the novel complexes as catalysts, particularly in the preparation of multimodal polymer products such as multimodal polyolefin compositions.
Many processes and catalysts are known for the preparation of homopolymeric or copolymeric olefins and other polymers. Ziegler-Natta catalyst compositions, developed in the 1950s, were found to be particularly useful in the preparation of polyolefins. These catalyst compositions comprise transition metal compounds such as titanium tetrachloride and an alkylaluminum (e.g., triethylaluminum) cocatalyst. The systems were found to be advantageous because of their high activity, and were largely consumed during polymerization.
Subsequent catalyst systems have been designed to provide more control over polymer structure and properties than could be achieved with Ziegler-Natta catalysts. These later catalysts have well-defined active sites and can be rationally designed to produce a specific polymer product, i.e., having predetermined structure and properties. Such catalysts include, for example, metal complexes known as xe2x80x9cmetallocenes.xe2x80x9d The term xe2x80x9cmetallocenexe2x80x9d was initially coined in the early 1950s to refer to dicyclopentadienyliron, or xe2x80x9cferrocene,xe2x80x9d a structure in which an iron atom is contained between and associated with two parallel cyclopentadienyl groups. The term is now used to refer generally to organometallic complexes in which a metal atom (not necessarily iron) is coordinated to at least one cyclopentadienyl ring ligand. A. D. Horton, xe2x80x9cMetallocene Catalysis: Polymers by Design,xe2x80x9d Trends Polym. Sci. 2(5):158-166 (1994), provides an overview of metallocene catalysts and their advantages, and focuses on now-conventional complexes of Group IV transition metal complexes and cyclopentadienyl ligands (Cp2MX2, wherein Cp represents a cyclopentadienyl ligand, M is Zr, Hf or Ti, and X is Cl or CH3). Unfortunately, however, although metallocenes do provide significant advantages relative to the traditional Ziegler-Natta catalysts, the high cost and difficulties associated with heterogenization of metallocenes, as well as the oxophilic nature of the early transition metals, have limited the applicability of metallocenes as commercial polymerization catalysts.
Because polyolefins such as polyethylene and polypropylene are such important commercial polymers, there is an ongoing need for improved polymerization techniques and polymerization catalysts. Recently, researchers have developed new catalysts suitable for olefin polymerization that are complexes of late transition metals and substituted diimine ligands. Such catalysts are described, for example, in Bres et al., PCT Publication No. WO 98/49208, published Nov. 5, 1998. Other similar catalysts, comprised of diimine ligands and selected metals, are described in Bennett, PCT Publication No. WO 98/27174, published Jun. 25, 1998, and in Brookhart et al., PCT Publication No. WO 98/30612, published Jul. 16, 1998.
A variety of catalyst systems have been used in the creation of xe2x80x9cmultimodalxe2x80x9d polymer compositions, i.e., compositions containing two or more molecular weight distributions as may be determined, for example, by the appearance of two or more peaks in a gel permeation chromatogram or the like. The term xe2x80x9cmultimodalityxe2x80x9d can also refer to other characteristics of a polymer composition as well, e.g., compositional distribution (the distribution of comonomers within a copolymer), tacticity distribution (wherein a polymer composition contains at least two segments of differing tacticity, long-chain branching distribution, and the like. Such multimodal polymers are frequently more useful than compositions that are not; for example, multimodal polymer compositions can have improved rheological behavior, higher mechanical strength and increased elasticity relative to corresponding compositions that are not multimodal.
Several processes are known for preparing multimodal polymer compositions using the catalyst systems discussed above. In U.S. Pat. No. 5,032,562 to Lo et al., a process involving the use of tandem reactors operated in series is described wherein, in a first reactor, an olefinic monomer is catalytically polymerized in the presence of hydrogen, with the product then transferred to a second reactor in which polymerization is conducted in the presence of hydrogen. In this way, a higher molecular weight polymer is produced in the first reactor, and the lower molecular weight polymer is produced in the second reactor.
U.S. Pat. No. 5,525,678 to Mink et al. provides a supported catalyst composition for producing a polyolefin resin having a high molecular weight component and a low molecular weight component, wherein the catalyst composition contains a first catalyst that is a metallocene and a second catalyst that is a non-metallocene. The ratio of the high molecular weight and low molecular weight components in the polymeric product is determined by the ratio of the concentration of the two metals in the two-component catalyst composition. In addition, U.S. Pat. No. 4,659,685 to Coleman, III et al. Describes a two-component catalyst composition for preparing polyolefins having a molecular weight distribution which is multimodal, the catalyst composition comprising a mixture of a supported titanium compound and a separately supported or non-supported organometallic compound.
U.S. Pat. No. 5,032,562 to Lo et al., cited above, also relates to a supported olefin polymerization catalyst composition for producing high density polyethylene (xe2x80x9cHDPExe2x80x9d) having a multimodal molecular weight distribution. The catalyst composition comprises: (1) a catalyst precursor supported on a porous carrier, and (2) a catalyst activator in the form of a mixture of conventional Ziegler-Natta cocatalysts. Katayama et al., xe2x80x9cThe Effect of Aluminum Compounds in the Copolymerization of Ethylene/xcex1-Olefins,xe2x80x9d in Macromol. Symp. 97:109-118 (1995), describes a similar system for preparing a polymer composition having a bimodal composition using a two-component catalyst comprised of a metallocene (CP2ZrCl2) and either [Ph3C+][B(C6F5)4xe2x88x92] or [PhMe2NH+][B(C6F5)4xe2x88x92].
PCT Publication No. WO 92/00333, inventors Canich et al., and EP 416,815, inventors Stevens et al., are also of interest insofar as the references describe metallocene catalysts for preparing polyolefins. Canich et al. describes metallocene catalyst compositions for producing high molecular weight polyolefins having a relatively narrow molecular weight distribution, wherein the catalyst composition is comprised of (1) a metallocene containing a Group IVB transition metal coordinated to a cyclopentadienyl ligand, and (2) a coordination complex such as an anionic complex containing a plurality of boron atoms, which serves as a catalyst activator. The metallocene catalysts described may be monoriuclear or binuclear (i.e., containing one or two metal atoms which serve as the active sites); the binuclear compounds dissociate during polymerization. Stevens et al. also pertains to metallocene catalysts to prepare addition polymers, particularly homopolymers and copolymers of olefins, diolefins, xe2x80x9chinderedxe2x80x9d aliphatic vinyl monomers and vinylidene aromatic monomers. The Stevens et al. catalysts are metal coordination complexes having constrained geometry, and are used in conjunction with a cocatalyst compound to form a complete catalytic system. The constrained geometry of the catalysts is stated to be of key importance insofar as the metal atom in the metallocene presumably is a more xe2x80x9cexposedxe2x80x9d active site.
Thus, the art provides metallocene catalyst compositions for producing polymers, particular polyolefins, that have a multimodal molecular weight distribution. However, such prior catalysts and catalyst compositions either require two or more components, e.g., two catalysts used in combination, or involve binuclear compounds that break apart into two separate components during the polymerization process (as in the bimetallic catalyst disclosed by Canich et al.), giving rise to potential manufacturing problems, e.g., phase separation or the like, and/or loss of control over the molecular weight distribution of the polymer composition prepared. In addition, the known metallocene catalysts can be relatively difficult and time-consuming to synthesize, requiring expensive equipment, extreme reaction conditions, and multi-step processes that ultimately result in a low yield of the desired product.
Accordingly, there is a need in the art for a simpler way of catalytically preparing multimodal polymer compositions while avoiding the high cost and difficulties associated with prior processes. An ideal method for preparing a multimodal polymeric product would involve a single catalyst that does not require the presence of a second catalyst, that retains its structure during the polymerization process, and is relatively simple to synthesize. The present invention is directed to such a catalyst.
The novel catalyst is comprised of an organometallic complex having two or more different active sites, at least one of which is composed of a transition metal atom coordinated to an unsaturated nitrogenous compound such as an imine, diimine or a 2,2xe2x80x2-bipyridine-containing compound. Use of such catalysts provide numerous advantages relative to the multimodal polymerization catalyst of the prior art, in that they:
1) allow for a exceptional control over the final polymer composition;
2) produce uniform multimodal products;
3) can be constructed via a straightforward, low cost synthesis;
4) are highly active polymerization catalysts;
5) can be used to catalyze reactions other than polymerization reactions, e.g., hydrogenation
6) enable preparation of commodity polymers such as linear low density polyethylene and isotactic polypropylene;
7) can be used as either supported or homogeneous polymerization catalysts;
8) are quite versatile and can be used in conjunction with a variety of monomer types; and
9) provide for all of the advantages typically associated with metallocene catalysts, i.e., versatility and use in conjunction with a variety of monomer types, the ability to control the degree of vinyl unsaturation in the polymeric product, and the like.
The invention thus represents a significant advance in the field of catalysis, as prior to the development of the catalysts disclosed and claimed herein, only a few of the aforementioned advantages could be achieved with a single catalyst system.
Accordingly, it is a primary object of the invention to provide a compound useful as a polymerization catalyst having two or more different active sites, at least one of which is comprised of a metal atom coordinated to an unsaturated nitrogenous ligand such as an imine, diimine or a 2,2xe2x80x2-bipyridine-containing compound.
It is a further object of the invention to provide a catalyst system which utilizes such a compound.
It is a further object of the invention to provide such compounds which are useful for preparing polyolefins or other polymers deriving from the polymerization of addition polymerizable monomers containing one or more degrees of unsaturation.
It is a still further object of the invention to provide a method for making an array of such compounds.
Additional objects, advantages and novel features of the invention will be set forth in part in the description which follows, and in part will become apparent to those skilled in the art upon examination of the following, or may be learned by practice of the invention.
In a first embodiment, then, novel compounds are provided comprised of multinuclear organometallic complexes, i.e., complexes having at least two active sites and associated organic ligands. The active sites have transition metal centers. The complex comprises an unsaturated nitrogenous compound, e.g., an imine, diimine or a 2,2xe2x80x2-bipyridine-containing compound, chelating the first transition metal center, with a second transition metal center chelated with either a second unsaturated nitrogenous compound or a cyclopentadienyl ligand. Additional metal centers may be present as well. Examples of suitable unsaturated nitrogenous ligands are those that contain a first coordinating atom that is a nitrogen atom contained within a Cxe2x95x90N group, and a second coordinating atom that is either a second nitrogen atom, that may or may not be present in a second Cxe2x95x90N group, or an oxygen, sulfur or phosphorus atom.
In another embodiment, the novel compounds are organometallic complexes comprising a first active site comprised of a transition metal atom M1, and an unsaturated nitrogenous ligand having the structure of formula (I) 
and a second active site comprised of a metal atom M2, wherein M2 is coordinated either to an unsaturated nitrogenous ligand having the structure of formula (I) or to one or more cyclopentadienyl moieties (II) 
wherein:
q is an optional double bond;
X is N, O, S or P, with the provisos that (a) when X is N or P, then either n is 1 or q is present as a double bond, but not both, and (b) when X is O or S, then n is zero and q is absent;
R1, R6, and R7 are independently hydrido, hydrocarbyl or substituted hydrocarbyl, and R2 and R5 are independently hydrido, halo, hydrocarbyl or substituted hydrocarbyl, or R1 and R2 and/or R5 and R6 may be taken together to form a linkage xe2x80x94Q*xe2x80x94, resulting in a five- or six-membered cyclic group, wherein Q* is xe2x80x94[(CR*)a*(Z)b*]xe2x80x94 in which a* is 2, 3 or 4, Z is N, O or S, b* is zero, 1 or2, the sum of a* and b* is 3 or 4, and R* is selected from the group consisting of hydrido, halo, hydrocarbyl, hydrocarbyloxy, trialkylsilyl, NR82, OR9, and NO2 wherein R8 and R9 are each independently hydrocarbyl, or wherein R* moieties on adjacent carbon atoms may be linked to form an additional five- or six-membered ring, or R2 and R5 may together form a linkage xe2x80x94Q*xe2x80x94 as just defined;
R3 and R4 are independently selected from the group consisting of hydrido and hydrocarbyl;
l is zero or 1;
m and n are independently zero or 1, preferably both zero; and
R and Rxe2x80x2 are independently selected from the group consisting of halogen, C1-C24 hydrocarbyl, C1-C24 hydrocarbyl substituted with one or more halogen atoms, and C1-C24 hydrocarbyl-substituted Group IVB elements, x is 0, 1, 2, 3 or 4, and y is 0, 1, 2, 3 or 4, with the proviso that the sum of x and y cannot exceed 4, or, when R and Rxe2x80x2 are ortho to each other and x and y are each 1 or greater, R and Rxe2x80x2 they can together form a five- or six-membered cyclic structure optionally substituted with one to four substituents selected from the group consisting of halogen, C1-C24 hydrocarbyl, C1-C24 hydrocarbyl substituted with one or more halogen atoms, and C1-C24 hydrocarbyl-substituted Group IVB elements.
In general, the aforementioned organic complexes may be represented by the structural formula (III) 
wherein:
B is a covalent bridging group comprising carbyl, silyl, disilyl, germanyl, ammonium, phosphonium, 
xe2x80x83or a C1-C30 hydrocarbylene, substituted hydrocarbylene, heterohydrocarbylene or substituted heterohydrocarbylene radical optionally containing a Group IVB element, a Group VB element, or both a Group IVB element and a Group VB element, and is capable of binding up to nmax substituents through single covalent bonds, wherein nmax is at least 4;
R1, R2, R3, R4, R5, R6, R7, X, 1, m, n and q are as defined above with respect to formula (I), and R, Rxe2x80x2, x and y are as defined above with respect to formula (II);
Q1, Q2, Q3 and Q4 are independently selected from the group consisting of univalent radicals;
Q5 is an optional ligand having the structure of formula (I);
The subscript k is zero or 1;
M1 is a transition metal;
M2 is a Group IIIA element, a Group IVA element, a Group VA element, a lanthanide, or an actinide;
Q is cyclopentadienyl, indenyl, fluorenyl, indolyl, aminoboratobenzyl, unsubstituted or substituted with R and/or R1 substituents as above, or Q may be J(Rx)z-2 wherein J is an element with a coordination number of three from Group VB or an element with a coordination number of two from Group VIB, Rx is selected from the group consisting of hydrogen, C1-C24 hydrocarbyl, C1-C24 hydrocarbyl substituted with one or more halogen atoms, and C1-C24 alkoxy, and z is the coordination number of J, and further wherein Q substituents on different Z groups are linked through a C1-C30 hydrocarbylene bridge,
a is at least 1, b is 0, 1 or 2, and the sum of a and b is 2 or 3.
The complex may also contain additional BL1 and/or BL2 moieties.
In a related embodiment, the novel compounds are organometallic complexes comprising a first active site comprised of a transition metal atom M1 and a 2,2xe2x80x2-bipyridine-containing ligand having the structure of formula (IV) 
and a second active site comprised of either a metal atom M2, wherein M2 is coordinated to one or more cyclopentadienyl ligands of formula (II), or a transition metal atom M1, wherein M1 is coordinated to an unsaturated nitrogenous ligand having the structure of formula (I), i and j are independently zero, 1, 2 or 3, and R10, R11, R12 and R13 are independently hydrido, hydrocarbyl or substituted hydrocarbyl.
In general, the aforementioned organic complexes may be represented by the structural formulas (V), (VI), (VII), (VIII) and (IX) 
wherein R1, R2, R3, R4, R5, R6, R7, X, l, m, n and q, are as defined above with respect to formula (I), R, Rxe2x80x2, x and y are as defined above with respect to formula (II), and a, b, M1, M2, Q. Q1, Q2 Q3 and Q4 are as defined above with respect to formula (III);
Q5 and Q6 are optional ligands having the structure of formula (I); and
k and h are independently zero or 1;
These complexes may also contain additional BL1 and/or BL2 moieties.
In another embodiment of the invention, a catalyst system is provided comprised of (1) a compound of the invention, as a catalyst, and (2) a catalyst activator, typically an aluminum-containing or boron-containing material. An exemplary catalyst is activator is methyl aluminoxane (xe2x80x9cMAOxe2x80x9d). When used in catalyzing polymerization, the catalyst system will be combined with an inert diluent, e.g., a hydrocarbon solvent, and optional additives such as polymerization rate accelerators.
An additional embodiment of the invention provides a method for preparing an polymer utilizing the catalyst system of the invention. The method comprises contacting selected addition polymerizable monomers having at least one degree of unsaturation with the inventive catalyst system under polymerization conditions effective to provide the desired polymer composition or other product.
With respect to the preparation of polyolefins, such polymers, as is known in the art, can be prepared having a variety of steric configurations deriving from the manner in which each monomer is added to the growing polymer chain. Four basic configurations are commonly recognized for polyolefins: atactic, in which monomer orientation is random; isotactic, in which each monomer is incorporated into the polymer in the same configuration; syndiotactic, in which the configuration of monomers alternates along a polymer chain; and hemi-isotactic, in which unique and regularly repeating stereochemistries are present within a single polymer chain. The present catalysts are useful for preparing polymers of desired tacticity, insofar as chiral catalysts can be used to catalyze stereospecific polymerization. Generally, a transition metal center having C2 symmetry will give rise to isotactic polymers, while those catalysts having Cs symmetry will give rise to syndiotactic polymers.
In addition to their utility as polymerization catalysts, the novel compounds are also useful in catalyzing other types of reactions, e.g., hydrogenation, dehydrocoupling, cyclization, substitution, carbomagnesation and hydrosilylation.
Before the present compounds, compositions and methods are disclosed and described, it is to be understood that unless otherwise indicated this invention is not limited to specific molecular structures, ligands, or the like, as such may vary. It is also to be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting.
It must be noted that, as used in the specification and the appended claims, the singular forms xe2x80x9ca,xe2x80x9d xe2x80x9canxe2x80x9d and xe2x80x9cthexe2x80x9d include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to xe2x80x9ca substituentxe2x80x9d includes one or more substituents, reference to xe2x80x9ca ligandxe2x80x9d includes one or more ligands, and the like.
The term xe2x80x9calkylxe2x80x9d as used herein refers to a branched or unbranched saturated hydrocarbon group of 1 to approximately 24 carbon atoms, typically 1 to approximately 12 carbon atoms, such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, t-butyl, octyl, decyl, tetradecyl, hexadecyl, eicosyl, tetracosyl and the like, as well as cycloalkyl groups such as cyclopentyl, cyclohexyl and the like. The term xe2x80x9clower alkylxe2x80x9d intends an alkyl group of 1 to 6 carbon atoms, preferably 1 to 4 carbon atoms.
The term xe2x80x9calkylenexe2x80x9d as used herein refers to a difunctional saturated branched or unbranched hydrocarbon chain containing from 1 to approximately 24 carbon atoms, typically 1 to approximately 12 carbon atoms, and includes, for example, methylene (xe2x80x94CH2xe2x80x94), ethylene (xe2x80x94CH2xe2x80x94CH2xe2x80x94), propylene (xe2x80x94CH2xe2x80x94CH2xe2x80x94CH2xe2x80x94), 2-methylpropylene (xe2x80x94CH2xe2x80x94CH(CH3)xe2x80x94CH2xe2x80x94), hexylene (xe2x80x94(CH2)6xe2x80x94), and the like. xe2x80x9cLower alkylenexe2x80x9d refers to an alkylene group of 1 to 6, more preferably 1 to 4, carbon atoms.
The term xe2x80x9calkenylxe2x80x9d as used herein refers to a branched or unbranched hydrocarbon group of 2 to approximately 24 carbon atoms, typically 2 to approximately 12 carbon atoms, containing at least one carbon-carbon double bond, such as ethenyl, n-propenyl, isopropenyl, n-butenyl, isobutenyl, t-butenyl, octenyl, decenyl, tetradecenyl, hexadecenyl, eicosenyl, tetracosenyl and the like. Preferred alkenyl groups herein contain 2 to 12 carbon atoms and 2 to 3 carbon-carbon double bonds. The term xe2x80x9clower alkenylxe2x80x9d intends an alkenyl group of 2 to 6 carbon atoms, preferably 2 to 4 carbon atoms, containing one xe2x80x94Cxe2x95x90Cxe2x80x94 bond. The term xe2x80x9ccycloalkenylxe2x80x9d intends a cyclic alkenyl group of 3 to 8, preferably 5 or 6, carbon atoms.
The term xe2x80x9calkenylenexe2x80x9d refers to a difunctional branched or unbranched hydrocarbon chain containing from 2 to approximately 24 carbon atoms, typically 2 to approximately 12 carbon atoms, and at least one carbon-carbon double bond. xe2x80x9cLower alkenylenexe2x80x9d refers to an alkenylene group of 2 to 6, more preferably 2 to 5, carbon atoms, containing one xe2x80x94Cxe2x95x90Cxe2x80x94 bond.
The term xe2x80x9calkynylxe2x80x9d as used herein refers to a branched or unbranched hydrocarbon group of 2 to approximately 24 carbon atoms, as above containing at least one xe2x80x94Cxe2x89xa1Cxe2x80x94 bond, such as ethynyl, n-propynyl, isopropynyl, n-butynyl, isobutynyl, t-butynyl, octynyl, decynyl and the like. Preferred alkynyl groups herein contain 2 to 12 carbon atoms. The term xe2x80x9clower alkynylxe2x80x9d intends an alkynyl group of 2 to 6, preferably 2 to 4, carbon atoms, and one xe2x80x94Cxe2x89xa1Cxe2x80x94 bond.
The term xe2x80x9calkynylenexe2x80x9d refers to a difunctional branched or unbranched hydrocarbon chain containing from 2 to approximately 24 carbon atoms as before and at least one carbon-carbon triple bond. xe2x80x9cLower alkynylenexe2x80x9d refers to an alkynylene group of 2 to 6, more preferably 2 to 5, carbon atoms, containing one xe2x80x94Cxe2x89xa1Cxe2x80x94 bond.
The term xe2x80x9calkoxyxe2x80x9d as used herein intends an alkyl group bound through a single, terminal ether linkage; that is, an xe2x80x9calkoxyxe2x80x9d group may be defined as xe2x80x94OR where R is alkyl as defined above. A xe2x80x9clower alkoxyxe2x80x9d group intends an alkoxy group containing one to six, more preferably one to four, carbon atoms.
The term xe2x80x9carrayxe2x80x9d used herein refers to a regular, orderly, two or three dimensional arrangements of compounds. Arrays typically comprise from 2 to 1,000,000,000 features.
The term xe2x80x9carylxe2x80x9d as used herein refers to an aromatic species containing 1 to 5 aromatic rings, either fused or linked, and either unsubstituted or substituted with 1 or more substituents typically selected from the group consisting of xe2x80x94(CH2)xxe2x80x94NH2, xe2x80x94(CH2)xxe2x80x94COOH, xe2x80x94NO2, halogen, alkyl, alkenyl, alkynyl, alkoxy, alkenyloxy, alkynyloxy, alkylthio, aryl, aralkyl, and the like, where x is an integer in the range of 0 to 6 inclusive as outlined above. Preferred aryl substituents contain 1 to 3 fused aromatic rings, and particularly preferred aryl substituents contain 1 aromatic ring or 2 fused aromatic rings. The terms xe2x80x9caralkylxe2x80x9d and xe2x80x9calkarylxe2x80x9d refer to moieties containing both alkyl and aryl species, typically containing less than about 24 carbon atoms, and more typically less than about 12 carbon atoms in the alkyl segment of the moiety, and typically containing 1 to 5 aromatic rings. The term xe2x80x9caralkylxe2x80x9d refers to aryl-substituted alkyl groups, while the term xe2x80x9calkarylxe2x80x9d refers to alkyl-substituted aryl groups. The terms xe2x80x9caralkylenexe2x80x9d and xe2x80x9calkarylenexe2x80x9d are used in a similar manner to refer to aryl-substituted alkylene and alkyl-substituted arylene moieties.
The term xe2x80x9carylenexe2x80x9d refers to a difunctional aromatic moiety; xe2x80x9cmonocyclic arylenexe2x80x9d refers to a cyclopentylene or phenylene group. These groups may be substituted with up to four ring substituents as outlined above.
The term xe2x80x9cheterocyclicxe2x80x9d refers to a five- or six-membered monocyclic structure or to an eight- to eleven-membered bicyclic structure which is either saturated or unsaturated. Each heterocycle consists of carbon atoms and from one to four heteroatoms selected from the group consisting of nitrogen, oxygen and sulfur. As used herein, the terms xe2x80x9cnitrogen heteroatomsxe2x80x9d and xe2x80x9csulfur heteroatomsxe2x80x9d include any oxidized form of nitrogen and sulfur, and the quaternized form of any basic nitrogen. Examples of heterocyclic groups include piperidinyl, pyrazinyl, morpholinyl and pyrrolidinyl.
xe2x80x9cHaloxe2x80x9d or xe2x80x9chalogenxe2x80x9d refers to fluoro, chloro, bromo or iodo, and usually relates to halo substitution for a hydrogen atom in an organic compound. Of the halos, chloro and fluoro are generally preferred.
xe2x80x9cHydrocarbylxe2x80x9d refers to univalent hydrocarbyl radicals containing 1 to about 30 carbon atoms, preferably 1 to about 20 carbon atoms, most preferably 1 to about 12 carbon atoms, including branched or unbranched, saturated or unsaturated species, such as alkyl groups, alkenyl groups, aryl groups, and the like. The term xe2x80x9clower hydrocarbylxe2x80x9d intends a hydrocarbyl group of 1 to 6 carbon atoms, preferably 1 to 4 carbon atoms. The term xe2x80x9chydrocarbylenexe2x80x9d intends a divalent hydrocarbyl moiety containing 1 to about 30 carbon atoms, preferably 1 to about 24 carbon atoms, most preferably 1 to about 12 carbon atoms, including branched or unbranched, saturated or unsaturated species, or the like. The term xe2x80x9clower hydrocarbylenexe2x80x9d intends a hydrocarbylene group of one to six carbon atoms, preferably one to four carbon atoms. xe2x80x9cSubstituted hydrocarbylxe2x80x9d refers to hydrocarbyl substituted with one or more substituent groups, and the terms xe2x80x9cheteroatom-containing hydrocarbylxe2x80x9d and xe2x80x9cheterohydrocarbylxe2x80x9d refer to hydrocarbyl in which at least one carbon atom is replaced with a heteroatom. Similarly, xe2x80x9csubstituted hydrocarbylenexe2x80x9d refers to hydrocarbylene substituted with one or more substituent groups, and the terms xe2x80x9cheteroatom-containing hydrocarbylenexe2x80x9d and xe2x80x9cheterohydrocarbylenexe2x80x9d refer to hydrocarbylene in which at least one carbon atom is replaced with a heteroatom.
By xe2x80x9csubstitutedxe2x80x9d as in xe2x80x9csubstituted hydrocarbylxe2x80x9d or xe2x80x9csubstituted hydrocarbylenexe2x80x9d is meant that the hydrocarbyl or hydrocarbylene group contains one or more substituent groups which are inert under the process conditions to which the compound containing these groups is subjected. xe2x80x9cMonosubstitutedxe2x80x9d refers to a hydrocarbyl or hydrocarbylene group having one substituent group and xe2x80x9cdisubstitutedxe2x80x9d refers to a hydrocarbyl or hydrocarbylene group containing two substituted groups. The substituent groups also do not substantially interfere with the process. Included in the meaning of xe2x80x9csubstitutedxe2x80x9d are heteroaromatic rings. Examples of substituents include, but are not limited to, amino (including primary amino and alkyl-substituted, typically lower alkyl-substituted, secondary and tertiary amino), alkyl (typically lower alkyl), alkoxy (typically lower alkoxy), alkenyl (typically lower alkenyl), aryl (e.g., phenyl), halo, haloalkyl, imino, nitro, and the like.
A xe2x80x9csubstratexe2x80x9d refers to a material having a rigid or semi-rigid surface. In some embodiments, at least one surface of the substrate will be substantially flat. In other embodiments, the substrate will be divided into physically separate synthesis regions. Division of the substrate into physically separate synthesis regions can be achieved with, for example, dimples, wells, raised regions, etched trenches, or the like. In some embodiments, small beads or pellets may be provided on the surface by, for example, placing the beads within dimples, wells or within or upon other regions of the substrate""s surface. Alternatively, the small beads or pellets may themselves be the substrate. An appropriate substrate can be made out of any material which is compatible with the process intended to occur thereon. Such materials include, but are not limited to, organic and inorganic polymers, quartz, glass, silica, etc. The choice of an appropriate substrate for certain given conditions will be apparent to those of skill in the art.
The term xe2x80x9csynthesis supportxe2x80x9d as used herein refers to a material such as, for example, silica, alumina, a resin or controlled pore glass (CPG) which is functionalized to allow a ligand or a ligand component to be attached either reversibly or irreversibly there to. A synthesis support can be held within or upon a xe2x80x9csubstrate.xe2x80x9d xe2x80x9cSynthesis support,xe2x80x9d xe2x80x9csupport,xe2x80x9d xe2x80x9cbead,xe2x80x9d and xe2x80x9cresinxe2x80x9d are used interchangeably herein.
The term xe2x80x9cunsaturated nitrogenous compoundxe2x80x9d refers to a compound having a Cxe2x95x90N moiety. Unsaturated nitrogenous compounds herein include both a true imine wherein the Cxe2x95x90N moiety is present in an acyclic molecular segment, as well as nitrogenous heterocycles in which the carbon-nitrogen bond is present in an aromatic ring, e.g., as in pyridine, pyrimidine, pyrazine, and the like.
xe2x80x9cOptionalxe2x80x9d or xe2x80x9coptionallyxe2x80x9d means that the subsequently described event or circumstance may or may not occur, and that the description includes instances where said event or circumstance occurs and instances where it does not. For example, the phrase xe2x80x9coptionally substituted hydrocarbylxe2x80x9d means that a hydrocarbyl moiety may or may not be substituted and that the description includes both unsubstituted hydrocarbyl and hydrocarbyl where there is substitution.
A xe2x80x9cheterogeneousxe2x80x9d catalyst as used herein refers to a catalyst which is supported on a carrier, typically although not necessarily a substrate comprised of an inorganic, solid, particulate porous material such as silicon and/or aluminum oxide.
A xe2x80x9chomogeneousxe2x80x9d catalyst as used herein refers to a catalyst which is not supported but is simply admixed with the initial monomeric components in a suitable solvent.
By xe2x80x9cstereospecificxe2x80x9d is meant a catalyst that will provide a polymer of predetermined, desired stereoregularity. The preferred catalysts herein are xe2x80x9cstereospecific.xe2x80x9d By xe2x80x9cisospecificxe2x80x9d is meant a catalyst that will provide an isotactic polymer. By xe2x80x9csyndiospecificxe2x80x9d is meant a catalyst that will provide a syndiospecific polymer. The most preferred catalysts herein are xe2x80x9cisospecificxe2x80x9d and xe2x80x9csyndiospecific.xe2x80x9d
The term xe2x80x9cmultimodal molecular weight distributionxe2x80x9d as used herein, and as alluded to above, refers to a polymer composition having two or more molecular weight distributions, as may be determined, for example, by the appearance of two or more peaks in a gel permeation chromatogram. Unless otherwise specified herein, the term xe2x80x9cmultimodalxe2x80x9d is intended to encompass the term xe2x80x9cbimodal.xe2x80x9d By the process of the invention, polymer compositions having a xe2x80x9cmultimodalxe2x80x9d molecular weight distribution can be generated using a multinuclear complexes of transition metals coordinated to at least one unsaturated nitrogenous ligand, in which polymerization takes place at different propagation rates at different active sites within the catalyst structure, or wherein the different active sites give rise to different termination rates, and/or wherein the different active sites have different responses to H2 (or other chain transfer agents). While the term xe2x80x9cmultimodalityxe2x80x9d generally refers to a multimodal molecular weight distribution, it should be emphasized that a polymer composition can also be xe2x80x9cmultimodalxe2x80x9d with respect to compositional distribution, tacticity distribution, long-chain branching distribution, or the like.
As used herein all reference to the Periodic Table of the Elements and groups thereof is to the version of the table published by the Handbook of Chemistry and Physics, CRC Press, 1995, which uses the IUPAC system for naming groups.
In a first embodiment, then, the novel compounds can be generally represented by the formula. (L1)aB(L2)b. They compounds are multinuclear organometallic complexes, i.e., complexes having at least two active sites and associated organic ligands. The complexes comprise an unsaturated nitrogenous ligand chelating a first transition metal center, with a second metal center chelated with either an unsaturated nitrogenous ligand or a cyclopentadienyl-based ligand. Additional metal centers may be present as well, along with additional unsaturated nitrogenous ligands and/or cyclopentadienyl-based ligands. Unsaturated nitrogenous ligands contain a first coordinating atom that is a nitrogen atom contained within a Cxe2x95x90N group, and a second coordinating atom that is either a second nitrogen atom, which may or may not be present in a second Cxe2x95x90N group, or an oxygen, sulfur or phosphorus atom. Each Cxe2x95x90N group may be a true imine functionality contained within an acyclic molecular segment, or may represent a linkage within a heterocycle such as a pyridine or pyrimidine ring.
Exemplary complexes are represented by structural formula (III) 
wherein:
B is a covalent bridging group comprising carbyl, silyl, disilyl, germanyl, ammonium, phosphonium, 
xe2x80x83or a C1-C30 hydrocarbylene, substituted hydrocarbylene, heterohydrocarbylene or substituted heterohydrocarbylene radical optionally containing a Group IVB element, a Group VB element, or both a Group IVB element and a Group VB element, and is capable of binding up to nmax substituents through single covalent bonds, wherein nmax is at least 4. Preferred B groups are C1-C30 hydrocarbylene, substituted hydrocarbylene, heterohydrocarbylene or substituted heterohydrocarbylene radicals optionally containing a Group IVB element and/or a Group VB element, and particularly preferred B groups are aryl C1-C30 heterohydrocarbylene groups, and silicon.
The cyclopentadienyl moiety, as shown, is optionally substituted with R and Rxe2x80x2 groups. Specifically, the integers x and y are independently 0, 1, 2, 3 or 4, with the proviso that the sum of x and y cannot exceed 4; preferably, x and y are independently 0, 1 or 2, and most preferably are 0 or 1. R and Rxe2x80x2 can be halogen, C1-C24 hydrocarbyl, either unsubstituted or substituted with one or more halogen atoms, lower alkyl groups and/or Group IVB elements. Alternatively, when an R and an Rxe2x80x2 substituent are both present, and ortho to each other on the cyclopentadienyl ring, they may together form a five- or six-membered cyclic structure. This cyclic structure may be unsubstituted or substituted with a halogen or C1-C24 hydrocarbyl group as explained above. Preferred R and Rxe2x80x2 substituents are halogen and C1-C2 alkyl; complexes wherein R and Rxe2x80x2 are ortho to each other and linked to form a cyclopentadienyl or indenyl group, either unsubstituted or substituted with halogen and/or lower alkyl moieties, are also preferred. Particularly preferred R and Rxe2x80x2 groups are halogen and lower alkyl; complexes wherein R and Rxe2x80x2 are ortho to each other and linked to form a cyclopentadienyl ring optionally substituted with a lower alkyl group are also particularly preferred.
Q is cyclopentadienyl, indenyl, fluorenyl, indolyl or aminoboratobenzyl, and may be unsubstituted or substituted with R and/or R1 substituents as above. Alternatively, Q is J(Rx)z-2 wherein J is an element with a coordination number of three from Group VB or an element with a coordination number of two from Group VIB, Rx is selected from the group consisting of hydrogen, C1-C24 hydrocarbyl, C1-C24 hydrocarbyl substituted with one or more, typically one to twelve, halogen atoms, and C1-C24 alkoxy, and z is the coordination number of J. Preferred Q substituents are cyclopentadienyl, indenyl, fluorenyl, aminoboratobenzyl or J(Rx)z-2 wherein J is nitrogen, phosphorus, oxygen or sulfur, and Rx is C1-C12 alkyl optionally substituted with one or more, typically one to six, halogen atoms. Particularly preferred Q groups are NRx moieties wherein Rx is lower alkyl or phenyl.
Q1, Q2, Q3 and Q4 are each a univalent radical, and are preferably independently selected from the group consisting of hydrido, halide, alkoxy, amido, and substituted or unsubstituted C1-C30 hydrocarbyl; if substituted, the substituents are typically although not necessarily electron-withdrawing groups such as a halogen atom, an alkoxy group, or the like, or the substituents may be Group IVB or Group VB elements. Alternatively, Q1 and Q2 and/or Q3 and Q4 may together form an alkylidene olefin (i.e., xe2x95x90CR2 wherein R is hydrogen or hydrocarbyl, typically lower alkyl), acetylene, or a five- or six-membered cyclic hydrocarbyl group. Preferred Q1, Q2, Q3 and Q4 moieties are hydrido, amido, C1-C12 alkyl, and C1-C12 alkyl substituted with one or more halogen and/or alkoxy groups, typically one to six such groups, and C1-C12 alkyl substituted with a Group IVB element. Particularly preferred Q1, Q2, Q3 and Q4 moieties are hydrido, amido, lower alkyl and lower alkoxy.
Q5 is an optional ligand having the structure of formula (I).
The subscripts k, l, m and n are independently zero or 1, preferably both m and n are zero, and letter xe2x80x9cqxe2x80x9d represents an optional double bond.
X is N, O, S or P, with the provisos that (a) when X is N or P, then either n is 1 or q is present as a double bond, but not both, and (b) when X is O or S, then n is zero and q is absent.
R1, R6 and R7 are independently hydrido, hydrocarbyl or substituted hydrocarbyl, as defined above, and R2 and R5 are independently hydrido, halo, hydrocarbyl or substituted hydrocarbyl, or R1 and R2 and/or R5 and R6 may be taken together to form a linkage xe2x80x94Q*xe2x80x94, resulting in a five- or six-membered cyclic group. As explained above, Q* is xe2x80x94[(CR*)a*(Z)b*]xe2x80x94 in which a* is 2, 3 or 4, Z is N, O or S, b* is zero, 1 or 2, the sum of a* and b* is 3 or 4, and R* is selected from the group consisting of hydrido, halo, hydrocarbyl, hydrocarbyloxy, trialkylsilyl, NR82, OR9, and NO2, wherein R8 or R9 are each independently hydrocarbyl, or wherein R moieties on adjacent carbon atoms may be linked to form an additional five- or six-membered ring. R2 and R5 may together form a linkage xe2x80x94Q*xe2x80x94 as just defined. Preferably, R6 is a substituted or unsubstituted aromatic group, e.g., phenyl, 1-naphthyl, 2-naphthyl, 2-ethylphenyl, 2,6-diisopropylphenyl, 2,6-di-n-butylphenyl, 2,6-dimethylphenyl, 2-t-butylphenyl, 2,6-diphenylphenyl, 2,4,6-trimethylphenyl, 2-trifluoromethylphenyl, 4-bromo-2,6-dimethylphenyl, 3,5-dichloro-2,6-diethylphenyl, or 2,6-bis(2,6-dimethylphenyl)phenyl.
Examples of R1, R6 and R7 thus include, but are not limited to, hydrido, methyl, ethyl, n-propyl, isopropyl, methoxy, ethoxy, isopropoxy, phenyl, benzyl, phenoxy, pyridyl, diisopropylphenyl, methoxyphenyl, trimethylsilyl, triethylsilyl, and the like; R2 and R5 substituents can include any of the foregoing as well as halogen substituents, i.e., chloro, fluoro, bromo and iodo, with chloro and fluoro preferred. When R1 and R2 and/or R5 and R6 are linked, the cyclic structures so formed may be alicyclic or aromatic, including, for example, furanyl, pyrrolyl, thiophenyl, imidazolyl, pyrazolyl, oxathiolyl, pyridinyl, methylpyridinyl, ethylpyridinyl, pyridazinyl, pyrimidinyl, pyrazinyl, piperidinyl, piperazinyl, morpholinyl, tetrahydrothiophenyl, tetrahydrofuranyl, tetrahydropyranyl, 1,4-dioxanyl, etc. When R2 and R5 are linked, the resulting structures are alicyclic and may or may not contain heteroatoms; such moieties include, for example, cyclopentane, cyclohexane, tetrahydrofuran, tetrahydropyran, tetrahydrothiophene, 1,4-dioxane, 1,2-dithiole, 1,3-dithiole, piperazine, morpholine, and the like.
R3 and R4 are independently selected from the group consisting of hydrido and hydrocarbyl, preferably hydrido or lower alkyl, or at least one of R3 and R4 may be bound through a lower alkylene linkage, preferably a methylene linkage, to an atom contained within L1 or L2.
M1 is a transition metal, including, but not limited to, Mb, Ta, Mo, W, Mn, Re, V and Cr.
M2 is a Group IIIA element, a Group IVA element, a Group VA element, a lanthanide, or an actinide. Particularly preferred M2 moieties are Zr, Hf and Ti.
The letter xe2x80x9caxe2x80x9d represents an integer of at least 1, xe2x80x9cbxe2x80x9d is zero, 1 or 2, and the sum of a and b is 2 or 3.
The complex may also contain additional BL1 and/or BL2 moieties.
One group of such compounds is represented by structural formula (V) 
wherein:
a, b, B, M1, M2, R, Rxe2x80x2, k, x, y, Q, Q1, Q2, Q3, Q4 and Q5 are as defined above with respect to formula (III);
R10, R11, R12 and R13 are independently hydrido, hydrocarbyl or substituted hydrocarbyl; and
i and j are independently zero, 1, 2 or 3.
In another embodiment, complexes of the invention have the structure of formula (VI) 
wherein:
R1, R2, R3, R4, R5, R6, R7, X, a, b, B, M1, k, l, m, n, q, Q1, Q2, Q3, Q4 and Q5 areas defined above with respect to formula (III);
Q6 is an optional ligand having the structure of formula (I);
h is zero or 1;
R10, R11, R12 and R13 are independently hydrido, hydrocarbyl or substituted hydrocarbyl; and
i and j are independently zero, 1, 2 or 3.
Another group of complexes is represented by structural formula (VII) 
wherein:
a, b, B, M1, M2, R, Rxe2x80x2, k, x, y, Q, Q1, Q2, Q3, Q4 and Q5 are as defined above with respect to formula (III);
R12 and R13 are independently hydrido, hydrocarbyl or substituted hydrocarbyl; and
i and j are independently zero, 1, 2 or 3.
In still another embodiment, complexes of the invention have the structure of formula (VIII) 
wherein:
R1, R2, R3, R4, R5, R6, R7, X a, b, B, M1, k, l, m, n, q, Q1, Q2, Q3, Q4 and Q5 areas defined above with respect to formula (III);
Q6 is an optional ligand having the structure of formula (I);
h is zero or 1;
R12 and R13 are independently hydrido, hydrocarbyl or substituted hydrocarbyl; and
i and j are independently zero, 1, 2 or 3.
In still another embodiment, complexes of the invention have the structure of formula (IX) 
wherein:
R1, R2, R3, R4, R5, R6, R7, X, a, b, B, M1, k, l, m, n, q, Q1, Q2, Q3, Q4 and Q5 are as defined above with respect to formula (III);
Q6 is an optional ligand having the structure of formula (I);
h is zero or 1;
R13 is independently hydrido, hydrocarbyl or substituted hydrocarbyl; and
j is zero, 1, 2 or 3.
In yet another embodiment, complexes of the invention have the structure of formula (IX) 
wherein:
a, b, B, M1, M2, R, Rxe2x80x2, k, x, y, Q, Q1, Q2, Q3, Q4 and Q5 are as defined above with respect to formula (III);
R13 is independently hydrido, hydrocarbyl or substituted hydrocarbyl; and
j is zero, 1,2 or 3.
Specific catalysts encompassed by formulae (III), (V), (VI), (VII), (VIII), (IX) and (X) include, but are not limited to, the following: 
The complexes of the invention may be prepared using relatively simple and straightforward synthetic processes known to those skilled in the art and/or described in the pertinent texts and literature. For example, the complexes may be prepared by first providing an unsaturated nitrogenous ligand, Ln, which can be obtained cornmercially or chemically synthesized. See, e.g., PCT Publication Nos. WO 98/27124, WO 98/30612 and WO 98/49208, and U.S. Pat. No. 5,866,663, which describe such ligands and synthesis thereof. For example, an unsaturated nitrogenous ligand having the structural formula (XI) 
wherein Rd and Re are defined as any of R1, R2, R5 and R6, may be synthesized by addition of the primary amine Rdxe2x80x94NH2 to the diketone of formula (XII) 
in a simple, straightforward, one-step reaction.
Other unsaturated nitrogenous ligands may be synthesized in a similar manner, by reaction of a suitable primary amine with a selected aldehyde or a ketone. For example, the asymmetric ligand of formula (XIII) 
may be readily synthesized from 2,6-diisopropylaniline and 2-pyrazinecarboxaldehyde, as described, for example, in Weidenbruch et al. (1993) Organometallic Chemistry 454:35. Patai, The Chemistry of the Carbon-Nitrogen Double Bond (1970), also provides information on various synthetic methods that can be used in the preparation of unsaturated nitrogenous compounds.
The next step of the synthesis involves the use of a halogenated compound B(Hal)2(a+b) as a starting material (wherein B, a and b are as defined earlier herein and xe2x80x9cHalxe2x80x9d represents a halogen atom). The compound is contacted with an alkali metal salt of the desired second ligand Lx, i.e., an unsaturated nitrogenous ligand or a cyclopentadienyl-based ligand to provide an intermediate LnaB(Hal)b. Next, the intermediate is successively reacted with an alkali metal salt of Ln, thus providing the intermediate LnaBLxb. This intermediate is deprotonated and metallated as described below.
In an alternative method, a starting material B(Hal)4 is caused to react with an alkali metal salt of the Ln ligand. The product is then contacted with an alkali metal salt of an aromatic compound Ar, containing one to three cyclopentadienyl rings, either substituted or unsubstituted, to provide an intermediate LnBAr2. (When it is desired that the end product contain different aromatic groups, successive reaction with different aromatic salts is carried out, i.e., LnB(Hal)2 is first reacted with an alkali metal salt of a first aromatic species Ar1, then with an alkali metal salt of a second aromatic species Ar2, and the like.) This intermediate is then used to prepare the compound LnaLBxb. Metallation is then carried out using metal complexes generally of the form MQxe2x80x2Qxe2x80x2Y2 wherein M is a transition metal Qxe2x80x2 is Q1, Q2, Q3 or Q4 as defined earlier herein, and the Y substituents are leaving groups that are typically halide, pseudohalide (e.g., lower alkoxy such as methoxy), flurohydrocarbylborate, etc. During the metallation reaction, the Y groups are eliminated.
Oxamides may also be used as starting materials. In this method, a oxallyl chloride is reacted with two equivalents of a primary amine in the presence of THF. If desired, equal molar equivalents of different primary amines may be sequentially added. Once the oxamide has been synthesized, it is reacted with PCl3 or POCl3 or the like to form a bis-imidoylchloride. The bis-imidoylchloride ligand may then be reacted with a diol bridging compound in the presence of triethylamine, a two molar equivalent of sodium hydride, and THF to form a bridged ligand complex. This complex may then be metallated as discussed above. Other suitable metallation reactions for preparing the present complexes will be known to those skilled in the art and/or described in or readily derived from the pertinent texts and literature.
The novel compounds of the invention, when used as polymerization catalysts, are used in conjunction with a conventional catalyst activator as will be appreciated by those skilled in the art. Thus, prior to use, the compounds of the invention are incorporated into a catalyst system that includes such an activator. Suitable catalyst activators include, but are not limited to, metal alkyls, hydrides, alkylhydrides, and alkylhalides, such as alkyllithium compounds, dialkylzinc compounds, trialkyl boron compounds, trialkylaluminum compounds, alkylaluminum halides and hydrides, and tetraalkylgermanium compounds. Specific examples of useful activators include n-butyllithium, diethylzinc, di-n-propylzinc, triethylboron, triethylaluminum, triisobutylaluminum, tri-n-hexylaluminum, ethylaluminum dichloride, dibromide and dihydride, isobutyl aluminum dichloride, dibromide and dihydride, di-n-propylaluminum chloride, bromide and hydride, diisobutyl-aluminum chloride, bromide and hydride, ethylaluminum sesquichloride, methyl aluminoxane (xe2x80x9cMAOxe2x80x9d), hexaisobutyl aluminoxane, tetraisobutyl aluminoxane, polymethyl aluminoxane, tri-n-octylaluminum, tetramethyl germanium, and the like. Other activators that are typically referred to as ionic cocatalysts may also be used; such compounds include, for example, (C6H6)3+, C6H5xe2x80x94NH2CH3+, and fluorohydrocarbylboron compounds such as tetra(pentafluorophenyl)borate, sodium tetrakis[(bis-3,5-trifluoromethyl)phenyl]borate, H+(OCH2CH3)2[(bis-3,5-trifluoromethyl)-phenyl]borate, trityltetra(pentafluorophenyl)borate and tris(pentafluorophenyl)boron. Mixtures of activators may, if desired, be used. Generally, the catalyst activator is such that upon combination with a compound of the invention, a catalytically active ionic species results.
For liquid phase or slurry polymerization, the catalyst and activator are generally mixed in the presence of inert diluents such as, for example, aliphatic or aromatic hydrocarbons, e.g., liquified ethane, propane, butane, isobutane, n-butane, n-hexane, isooctane, cyclohexane, methylcyclohexane, cyclopentane, methylcyclopentane, cycloheptane, methylcycloheptane, benzene, ethylbenzene, toluene, xylene, kerosene, Isopar(copyright) M, Isopar(copyright) E, and mixtures thereof. Liquid olefins, or the like, which serve as the monomers or comonomers in the polymerization process may also serve as the diluent; such olefins include, for example, ethylene, propylene, butene, 1-hexene and the like. The amount of catalyst in the diluent will generally be in the range of about 0.01 to 1.0 mmoles/liter, with activator added such that the ratio of catalyst to activator is in the range of from about 10:1 to 1:2000, preferably in the range of from about 1:1 to about 1:200, on a molar basis.
Preparation of the catalyst/activator/diluent mixture is normally carried out under anhydrous conditions in the absence of oxygen, at temperatures in the range of from about xe2x88x9290xc2x0 C. to about 300xc2x0 C., preferably in the range of from about xe2x88x9210xc2x0 C. to about 200xc2x0 C.
The catalyst, activator and diluent are added to a suitable reaction vessel, in any order, although, as noted above, the catalyst and activator are usually mixed in the diluent and the mixture thus prepared then added to the reactor.
A further embodiment of the invention provides a method of synthesizing arrays of metal-ligand compounds using the multimodal catalysts of the invention. In the method at least two different metal-binding amino alcohol-derived ligands are synthesized on or delivered to a substrate. These ligands may be supported or unsupported prior to contact with the substrate. Once in contact with the substrate, the ligands are metallated, as described above, forming metal-ligand compounds. Each of the ligands may be metallated with the same or different Group IV A, Group VA or Group VIA metals.
In a still further embodiment, methods are provided for synthesizing and screening arrays of multimodal metal-ligand compounds. In the method at least two alkali metal salts of different Ln metal-binding, unsaturated nitrogenous ligands are synthesized on or delivered to a substrate. These ligands may be supported or unsupported prior to contact with the substrate. Once in contact with the substrate, the ligands are contacted with a halogenated compound B(Hal)2(a+b) (wherein B, a and b are as defined earlier herein and xe2x80x9cHalxe2x80x9d represents a halogen atom) to provide intermediate LnaB(Hal)b compounds Next, the intermediates are successively reacted with alkali metal salts of the desired second ligands Lx, i.e., unsaturated nitrogenous ligands or a cyclopentadienyl-based ligands, thus providing intermediate LnaBLxb compounds. These intermediates are deprotonated and metallated as described above. Each of the ligands may be metallated with the same or different Group IV A, Group VA or Group VIA metals. The multimodal metal-ligand compounds may be activated using one or more conventional catalyst activators.
In a still further embodiment, methods are provided for forming and screening arrays of multimodal metal-ligand compounds of the invention. In the method at least two different multimodal metal-ligand compounds are synthesized on a substrate. Again, these ligands may be supported or unsupported prior to contact with the substrate. The multimodal metal-ligand compounds may be synthesized in an array or may be placed in an array arrangement after synthesis. The multimodal metal-ligand compounds may be screened for purity and identity using conventional. Typical screening and characterizing techniques such as mass spectrometry, calorimetry, digital autoradiography, polarimetry, imaging polarimetry, infrared spectroscopy, reflectance spectroscopy, uv-vis spectroscopy, chemisorption, surface area (BET) measurements, uv-vis fluorescence, phosphorescence, chemiluminescence, Raman spectroscopy, NIR spectroscopy, magnetic resonance imaging, NMR spectroscopy, Electron Spin Resonance (ESR) spectroscopy, gas chromatography, high performance liquid chromatography (HPLC), x-ray diffraction, neutron diffraction, refractometry, circular dichroism, electron spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM), scanning tunneling microscopy (STM), and the like.
The multimodal metal-ligand compounds may then be used in catalyzing reactions. During and after the catalyzed reactions, the multimodal metal-ligand compounds and the resulting products can be screened for useful properties using conventional screening and characterizing techniques such as chemical or biological testing; mass spectrometry; reaction calorimetry; parallel reaction calorimetry; parallel differential scanning calorimetry; viscosity measurement; digital autoradiography; thermal imaging; polarimetry; imaging polarimetry; infrared spectroscopy; IR imaging; reflectance spectroscopy; uv-vis spectroscopy; chemisorption; surface area (BET) measurements; uv-vis fluorescence; phosphorescence; chemiluminescence; Raman spectroscopy; NIR spectroscopy; magnetic resonance imaging; NMR spectroscopy; gas chromatography; high performance liquid chromatography (HPLC); gel permeation chromatography (GPC); TREF; x-ray diffraction; neutron diffraction; refractometry; circular dichroism; turbidimetry; electron spectroscopy; scanning electron microscopy (SEM); transmitting electron microscopy (TEM); scanning tunneling microscopy (STM).
The array of products can also be used to screen for important chemical and physical properties such as solvent extractables, solubility, porosity, weatherability, uv-vis stability, scratch resistance, abrasion resistance, wettability, hardness, color, dielectric constant, moisture absorption, solvent swelling, gloss, adhesion, heat aging, shear, stain resistance, and scrub resistance. Screening may be performed either simultaneously, serially and/or in a spatially selective manner, i.e., wherein the detector used is distanced from the array, the array is screened and the detector is then repositioned so that a different portion of the array is screened.
The novel catalysts are used to prepare polymeric compositions using conventional polymerization techniques known to those skilled in the art and/or described in the pertinent literature. The monomer(s), catalyst and catalyst activator are contacted at a suitable temperature at reduced, elevated or atmospheric pressure, under an inert atmosphere, for a time effective to produce the desired polymer composition. The catalyst may be used as is or supported on a suitable support. In one embodiment, the novel catalysts are used as homogeneous catalysts, i.e., as unsupported catalysts, in a gas phase or liquid phase polymerization process. A solvent may, if desired, be employed. The reaction may be conducted under solution or slurry conditions, in a suspension using a perfluorinated hydrocarbon or similar liquid, in the gas phase, or in a solid phase powder polymerization.
Liquid phase polymerization generally involves contacting the monomer or monomers with the catalyst/activator mixture in the polymerization diluent, and allowing reaction to occur under polymerization conditions, i.e., for a time and at a temperature sufficient to produce the desired polymer product. Polymerization may be conducted under an inert atmosphere such as nitrogen, argon, or the like, or may be conducted under vacuum. Preferably, polymerization is conducted in an atmosphere wherein the partial pressure of reacting monomer is maximized. Liquid phase polymerization may be carried out at reduced, elevated or atmospheric pressures. In the absence of added solvent, i.e., when the olefinic monomer serves as the diluent, elevated pressures are preferred. Typically, high pressure polymerization in the absence of solvent is carried out at temperatures in the range of about 0xc2x0 C. to about 300xc2x0 C., preferably in the range of about 50xc2x0 C. to about 200xc2x0 C., and at pressures on the order of 1 to 5,000 atm, typically in the range of about 10 to 500 atm. When solvent is added, polymerization is generally conducted at temperatures in the range of about 0xc2x0 C. to about 200xc2x0 C., preferably in the range of about 50xc2x0 C. to about 100xc2x0 C., and at pressures on the order of 10 to 500 atm.
Polymerization may also take place in the gas phase, e.g., in a fluidized or stirred bed reactor, using temperatures in the range of approximately 60xc2x0 C. to 120xc2x0 C. and pressures in the range of approximately 10 to 1000 atm.
The monomer or comonomers used are addition polymerizable monomers containing one or more degrees of unsaturation. Olefinic or vinyl monomers are preferred, and particularly preferred monomers are a-olefins having from about 2 to about 20 carbon atoms, such as, for example, linear or branched olefins including ethylene, propylene, 1-butene, 3-methyl-1-butene, 1,3-butadiene, 1-pentene, 4-methyl-1-pentene, 1-hexene, 4-methyl-1-hexene, 1,4-hexadiene, 1,5-hexadiene, 1-octene, 1,6-octadiene, 1-nonene, 1-decene, 1,4-dodecadiene, 1-hexadecene, 1-octadecene, and mixtures thereof. Cyclic olefins and diolefins may also be used; such compounds include, for example, cyclopentene, 3-vinylcyclohexene, norbornene, 5-vinyl-2-norbornene, 5-ethylidene-2-norbornene, dicyclopentadiene, 4-vinylbenzocyclobutane, tetracyclododecene, dimethano-octahydronaphthalene, and 7-octenyl-9-borabicyclo-(3,3,1)nonane. Aromatic monomers that may be polymerized using the novel metallocenes include styrene, o-methyl styrene, m-methyl styrene, p-methyl styrene, p-tert-butylstyrene, m-chlorostyrene, p-chlorostyrene, p-fluorostyrene, indene, 4-vinylbiphenyl, acenaphthalene, vinylfluorene, vinylanthracene, vinylphenanthrene, vinylpyrene and vinylchrisene. Other monomers that may be polymerized using the present catalysts include methylmethacrylate, ethylacrylate, vinyl silane, phenyl silane, trimethylallyl silane, acrylonitrile, maleimide, vinyl chloride, vinylidene chloride, tetrafluoroethylene, isobutylene, carbon monoxide, acrylic acid, 2-ethylhexylacrylate, methacrylonitrile and methacrylic acid.
In gas and slurry phase polymerizations, the catalyst is used in a heterogeneous process, i.e., supported on an inert inorganic substrate. Conventional materials can be used for the support, and are typically particulate, porous materials; examples include oxides of silicon and aluminum, or halides of magnesium and aluminum. Particularly preferred supports from a commercial standpoint are silicon dioxide and magnesium dichloride.
The polymeric product resulting from the aforementioned reaction may be recovered by filtration or other suitable techniques. If desired, additives and adjuvants may be incorporated into the polymer composition prior to, during, or following polymerization; such compounds include, for example, pigments, antioxidants, lubricants and plasticizers.
As explained earlier herein, the invention enables preparation of polymer compositions that are multimodal in nature, typically, but not necessarily, having a multimodal molecular weight distribution. That is, the catalysts used herein contain two or more active sites at which propagation rates differ, or that have different temperature sensitivities and/or H2 responsiveness or the like. In this way, the type and degree of multimodality in the polymeric product can be controlled as desired. Multimodal polymer compositions are useful insofar as rheological behavior, mechanical strength and elasticity can be improved relative to corresponding compositions that are not multimodal.
The compounds of the invention are also useful in catalyzing other types of reactions, i.e., reactions other than polymerizations. Such reactions include, but are not limited to, hydrogenation, dehydrocoupling, cyclization, substitution, carbomagnesation and hydrosilylation. Methods for using the metal complexes of the invention to catalyze the aforementioned reactions and others will be known to those skilled in the art and/or described in the pertinent texts and literature.